Minimally Invasive Surgery

Minimally Invasive Surgery US Medical PG Question 1: A 36-year-old woman is brought to the emergency department 20 minutes after being involved in a high-speed motor vehicle collision. On arrival, she is unconscious. Her pulse is 140/min, respirations are 12/min and shallow, and blood pressure is 76/55 mm Hg. 0.9% saline infusion is begun. A focused assessment with sonography shows blood in the left upper quadrant of the abdomen. Her hemoglobin concentration is 7.6 g/dL and hematocrit is 22%. The surgeon decided to move the patient to the operating room for an emergent explorative laparotomy. Packed red blood cell transfusion is ordered prior to surgery. However, a friend of the patient asks for the transfusion to be held as the patient is a Jehovah's Witness. The patient has no advance directive and there is no documentation showing her refusal of blood transfusions. The patient's husband and children cannot be contacted. Which of the following is the most appropriate next best step in management?

• A. Administer hydroxyethyl starch
• B. Transfusion of packed red blood cells (Correct Answer)
• C. Consult hospital ethics committee
• D. Administer high-dose iron dextran

Minimally Invasive Surgery Explanation: ***Transfusion of packed red blood cells*** - This patient is in **hemorrhagic shock** (tachycardia, hypotension, low hemoglobin, and hematocrit with evidence of active bleeding), requiring emergent blood transfusion to prevent irreversible organ damage and death. - In an **emergency setting** with an **unconscious patient** and **no documented refusal** of blood products, the principle of **presumed consent** for life-saving treatment takes precedence, especially when next of kin cannot be reached. *Administer hydroxyethyl starch* - **Colloids** like hydroxyethyl starch can temporarily increase intravascular volume but do not provide oxygen-carrying capacity, which is critically needed for a patient with severe anemia and hemorrhagic shock. - While useful for volume expansion, it is **not a substitute for blood products** in severe bleeding and can have adverse effects such as kidney injury. *Consult hospital ethics committee* - Consulting an ethics committee is appropriate for **complex ethical dilemmas** when there is time for deliberation and the patient's life is not in immediate danger. - In this acute, life-threatening emergency, **delaying treatment** to consult an ethics committee would jeopardize the patient's life and is not appropriate. *Administer high-dose iron dextran* - **Iron dextran** is used to treat iron-deficiency anemia and works by supporting red blood cell production over several days to weeks. - It is **ineffective in acute hemorrhagic shock** where immediate restoration of oxygen-carrying capacity is required.

Minimally Invasive Surgery US Medical PG Question 2: During a surgical procedure to repair an abdominal aortic aneurysm, the surgeon must be careful to avoid injury to which of the following arterial structures that originates near the level of the renal vessels?

• A. Left renal artery (Correct Answer)
• B. Celiac trunk
• C. Right renal artery
• D. Superior mesenteric artery

Minimally Invasive Surgery Explanation: ***Left renal artery*** - The **left renal artery** arises from the aorta usually just below the superior mesenteric artery, making it susceptible to injury during an **abdominal aortic aneurysm (AAA) repair** if the aneurysm extends proximally. - Its proximity to the typical location of AAA, often near or involving the **infrarenal aorta**, necessitates careful identification and protection during clamping or graft placement. *Celiac trunk* - The **celiac trunk** originates higher up from the aorta, typically at the level of **T12-L1 vertebrae**, well above the common infrarenal AAA repair site. - While important, it is generally less directly threatened during a typical infrarenal AAA repair compared to arteries immediately adjacent to or within the aneurysm sac. *Right renal artery* - The **right renal artery** also originates from the aorta near the level of the renal veins, but it is typically located more posteriorly and usually passes behind the inferior vena cava. - Although it can be at risk, the left renal artery's course is often more anterior and directly in the field of dissection for the **aortic neck** during AAA repair. *Superior mesenteric artery* - The **superior mesenteric artery (SMA)** originates from the aorta proximal to the renal arteries, typically around the L1 vertebral level. - While crucial, its origin is usually cephalad to the infrarenal aneurysm neck, making it generally less prone to direct injury during infrarenal AAA repair, though flow must be monitored.

Minimally Invasive Surgery US Medical PG Question 3: A research team develops a new monoclonal antibody checkpoint inhibitor for advanced melanoma that has shown promise in animal studies as well as high efficacy and low toxicity in early phase human clinical trials. The research team would now like to compare this drug to existing standard of care immunotherapy for advanced melanoma. The research team decides to conduct a non-randomized study where the novel drug will be offered to patients who are deemed to be at risk for toxicity with the current standard of care immunotherapy, while patients without such risk factors will receive the standard treatment. Which of the following best describes the level of evidence that this study can offer?

• A. Level 1
• B. Level 3 (Correct Answer)
• C. Level 5
• D. Level 4
• E. Level 2

Minimally Invasive Surgery Explanation: ***Level 3*** - A **non-randomized controlled trial** like the one described, where patient assignment to treatment groups is based on specific characteristics (risk of toxicity), falls into Level 3 evidence. - This level typically includes **non-randomized controlled trials** and **well-designed cohort studies** with comparison groups, which are prone to selection bias and confounding. - The study compares two treatments but lacks randomization, making it Level 3 evidence. *Level 1* - Level 1 evidence is the **highest level of evidence**, derived from **systematic reviews and meta-analyses** of multiple well-designed randomized controlled trials or large, high-quality randomized controlled trials. - The described study is explicitly stated as non-randomized, ruling out Level 1. *Level 2* - Level 2 evidence involves at least one **well-designed randomized controlled trial** (RCT) or **systematic reviews** of randomized trials. - The current study is *non-randomized*, which means it cannot be classified as Level 2 evidence, as randomization is a key criterion for this level. *Level 4* - Level 4 evidence includes **case series**, **case-control studies**, and **poorly designed cohort or case-control studies**. - While the study is non-randomized, it is a controlled comparative trial rather than a case series or retrospective case-control study, placing it at Level 3. *Level 5* - Level 5 evidence is the **lowest level of evidence**, typically consisting of **expert opinion** without explicit critical appraisal, or based on physiology, bench research, or animal studies. - While the drug was initially tested in animal studies, the current human comparative study offers a higher level of evidence than expert opinion or preclinical data.

Minimally Invasive Surgery US Medical PG Question 4: A pharmaceutical company conducts a randomized clinical trial to demonstrate that their new anticoagulant drug, Aclotsaban, prevents more thrombotic events following total knee arthroplasty than the current standard of care. A significant number of patients are lost to follow-up, and many fail to complete treatment according to the study arm to which they were assigned. Despite these protocol deviations, the results for the patients who completed the course of Aclotsaban are encouraging. Which of the following analytical approaches is most appropriate for the primary analysis to establish the efficacy of Aclotsaban?

• A. Intention-to-treat analysis (Correct Answer)
• B. Sub-group analysis
• C. Per-protocol analysis
• D. As-treated analysis
• E. Non-inferiority analysis

Minimally Invasive Surgery Explanation: ***Intention-to-treat analysis*** - **Intention-to-treat (ITT) analysis** is the gold standard for the **primary analysis in superiority trials** and includes all patients in the groups to which they were originally randomized, regardless of protocol deviations, loss to follow-up, or treatment discontinuation. - ITT preserves **randomization balance**, prevents bias from selective dropout (patients may drop out due to adverse effects or lack of efficacy), and provides a **conservative, realistic estimate** of treatment effect in actual clinical practice. - For **regulatory approval and establishing efficacy**, ITT is the most appropriate primary analysis method even when dropout rates are high, as it maintains the integrity of the randomized comparison. *Per-protocol analysis* - **Per-protocol analysis** includes only patients who completed the study exactly as planned without protocol deviations. - While the encouraging results in completers are noted, per-protocol analysis can **introduce significant bias** by excluding patients who dropped out due to adverse events or lack of efficacy, potentially **overestimating treatment benefit**. - Per-protocol is typically used as a **secondary/supportive analysis**, not the primary method for establishing superiority. *As-treated analysis* - **As-treated analysis** categorizes patients according to the treatment they actually received rather than their randomized assignment. - This violates the principle of randomization and can introduce **confounding bias**, as actual treatment received may be influenced by prognostic factors. *Sub-group analysis* - **Sub-group analysis** evaluates treatment effects within specific patient subsets. - This is **hypothesis-generating** rather than confirmatory and increases the risk of false-positive findings (multiple comparisons problem) unless pre-specified in the protocol. *Non-inferiority analysis* - **Non-inferiority analysis** tests whether a new treatment is not worse than control by more than a pre-specified margin. - The goal here is to demonstrate **superiority** (better than standard care), not non-inferiority, making this approach inappropriate.

Minimally Invasive Surgery US Medical PG Question 5: A 27-year-old man presents to the emergency department after being stabbed. The patient was robbed at a local pizza parlor and was stabbed over 10 times with a large kitchen knife with an estimated 7 inch blade in the ventral abdomen. His temperature is 97.6°F (36.4°C), blood pressure is 74/54 mmHg, pulse is 180/min, respirations are 19/min, and oxygen saturation is 98% on room air. The patient is intubated and given blood products and vasopressors. Physical exam is notable for multiple stab wounds over the patient's abdomen inferior to the nipple line. Which of the following is the best next step in management?

• A. Exploratory laparotomy (Correct Answer)
• B. Diagnostic peritoneal lavage
• C. CT scan of the abdomen and pelvis
• D. Exploratory laparoscopy
• E. FAST exam

Minimally Invasive Surgery Explanation: ***Exploratory laparotomy*** - The patient presents with **multiple stab wounds** to the abdomen and signs of **hemorrhagic shock** (BP 74/54 mmHg, HR 180/min), which are clear indications for immediate surgical intervention. - An exploratory laparotomy allows for direct visualization and repair of internal injuries, which is critical in this life-threatening situation. *Diagnostic peritoneal lavage* - While DPL can detect intra-abdominal bleeding, it is an **invasive procedure** and may delay definitive treatment in a hemodynamically unstable patient with obvious penetrating trauma. - It is **less specific** than a laparotomy for identifying the exact location and nature of injuries, and it has largely been replaced by imaging studies or direct surgical exploration in unstable patients. *CT scan of the abdomen and pelvis* - A CT scan requires a **hemodynamically stable** patient and time for scanning and interpretation, which this patient does not have. - Delaying definitive treatment for imaging in a patient with severe shock could lead to worse outcomes. *Exploratory laparoscopy* - Although less invasive, laparoscopy can be time-consuming and may not be feasible or safe in a patient with **profound hemorrhagic shock** and extensive injuries, especially if major vascular or visceral damage is suspected. - Conversion to a **laparotomy** is often necessary in cases of significant injury, making immediate open exploration more efficient. *FAST exam* - A FAST exam can rapidly detect free fluid in the abdomen, suggesting internal bleeding, but it does **not provide specific information** about the source or extent of the injuries. - While useful in the initial assessment, a positive FAST exam in a hemodynamically unstable patient with penetrating trauma directly points to the need for immediate surgical intervention, not further diagnostic delay.

Minimally Invasive Surgery US Medical PG Question 6: A 32-year-old woman comes to the physician for a screening health examination that is required for scuba diving certification. The physician asks her to perform a breathing technique: following deep inspiration, she is instructed to forcefully exhale against a closed airway and contract her abdominal muscles while different cardiovascular parameters are evaluated. Which of the following effects is most likely after 10 seconds in this position?

• A. Decreased intra-abdominal pressure
• B. Decreased left ventricular stroke volume (Correct Answer)
• C. Decreased pulse rate
• D. Decreased systemic vascular resistance
• E. Increased venous return to left atrium

Minimally Invasive Surgery Explanation: ***Decreased left ventricular stroke volume*** - After 10 seconds of performing the **Valsalva maneuver**, the increased intrathoracic pressure significantly reduces **venous return** to the heart. - Reduced venous return leads to decreased **ventricular filling** (preload), which in turn diminishes **left ventricular stroke volume** and cardiac output. *Decreased intra-abdominal pressure* - The instruction to "contract her abdominal muscles" during forceful exhalation against a closed airway (Valsalva maneuver) directly leads to an **increase** in **intra-abdominal pressure**, not a decrease. - This increase in intra-abdominal pressure further impedes venous return from the lower extremities to the heart. *Decreased pulse rate* - In the initial phase of the Valsalva maneuver (first 5-10 seconds), the decrease in cardiac output triggers a **reflex tachycardia** to maintain blood pressure, leading to an **increased pulse rate**. - A decrease in pulse rate (bradycardia) is more characteristic of the release phase, not during the sustained strain. *Decreased systemic vascular resistance* - During the Valsalva maneuver, the body attempts to compensate for the drop in cardiac output and blood pressure by increasing **sympathetic tone**, which causes **vasoconstriction** and thus **increases systemic vascular resistance**. - A decrease in systemic vascular resistance would further drop blood pressure and is not the physiological response during this phase. *Increased venous return to left atrium* - The Valsalva maneuver dramatically **reduces venous return** to both the right and left atria due to the high intrathoracic pressure compressing the great veins. - This decreased venous return is the primary mechanism leading to the subsequent fall in cardiac output during the maneuver.

Minimally Invasive Surgery US Medical PG Question 7: An orthopaedic surgeon at a local community hospital has noticed that turnover times in the operating room have been unnecessarily long. She believes that the long wait times may be due to inefficient communication between the surgical nursing staff, the staff in the pre-operative area, and the staff in the post-operative receiving area. She believes a secure communication mobile phone app would help to streamline communication between providers and improve efficiency in turnover times. Which of the following methods is most appropriate to evaluate the impact of this intervention in the clinical setting?

• A. Plan-Do-Study-Act cycle (Correct Answer)
• B. Failure modes and effects analysis
• C. Standardization
• D. Forcing function
• E. Root cause analysis

Minimally Invasive Surgery Explanation: ***Plan-Do-Study-Act cycle*** - The **Plan-Do-Study-Act (PDSA) cycle** is a structured, iterative model used for continuous improvement in quality and efficiency, making it ideal for evaluating the impact of a new intervention like a communication app. - This cycle allows for small-scale testing of changes, observation of results, learning from the observations, and refinement of the intervention before full implementation. *Failure modes and effects analysis* - **Failure modes and effects analysis (FMEA)** is a prospective method to identify potential failures in a process, predict their effects, and prioritize actions to prevent them. - While useful for process improvement, FMEA is typically performed *before* implementing a change to identify risks, rather than to evaluate the impact of an already implemented intervention. *Standardization* - **Standardization** involves creating and implementing consistent processes or protocols to reduce variability and improve reliability. - While the communication app might contribute to standardization, standardization itself is a *method of improvement* rather than a method for *evaluating the impact* of an intervention. *Forcing function* - A **forcing function** is a design feature that physically prevents an error from occurring, making it impossible to complete a task incorrectly. - An app that streamlines communication does not act as a forcing function, as it facilitates a process rather than physically preventing an incorrect action. *Root cause analysis* - **Root cause analysis (RCA)** is a retrospective method used to investigate an event that has already occurred (e.g., an adverse event) to identify its underlying causes. - This method is used *after* a problem has manifested to understand *why* it happened, not to evaluate the *impact* of a new intervention designed to prevent future problems.

Minimally Invasive Surgery US Medical PG Question 8: A CT scan of the abdomen reveals a mass in the pancreatic uncinate process. Which of the following structures is most likely to be compressed by this mass?

• A. Common bile duct
• B. Portal vein
• C. Splenic vein
• D. Superior mesenteric vein (Correct Answer)

Minimally Invasive Surgery Explanation: ***Superior mesenteric vein*** - The **uncinate process** of the pancreas hooks around the **superior mesenteric vessels**. Therefore, a mass in this region would most directly compress the **superior mesenteric vein (SMV)** and artery (SMA). - Compression of the SMV can lead to **venous outflow obstruction** from the small intestine, potentially causing **bowel ischemia** or edema. *Common bile duct* - The **common bile duct** passes through the **head of the pancreas**, not typically the uncinate process. - Compression of the common bile duct would more commonly be associated with masses in the **head of the pancreas**, leading to **jaundice**. *Portal vein* - The **portal vein** is formed by the union of the **splenic vein** and the **superior mesenteric vein**, generally posterior to the neck of the pancreas. - While pancreatic masses can affect the portal vein, a mass specifically in the uncinate process would more directly impinge on the SMV before significantly affecting the main portal vein, which is superior and posterior to the uncinate process. *Splenic vein* - The **splenic vein** runs along the **posterior aspect of the body and tail of the pancreas**. - A mass in the uncinate process, located at the inferior margin of the head, is relatively distant from the splenic vein.

Minimally Invasive Surgery US Medical PG Question 9: A 39-year-old woman presents to the emergency department with right upper quadrant abdominal discomfort for the past couple of hours. She says that the pain is dull in nature and denies any radiation. She admits to having similar episodes of pain in the past which subsided on its own. Her temperature is 37°C (99.6°F), respirations are 16/min, pulse is 78/min, and blood pressure is 122/98 mm Hg. Physical examination is normal except for diffuse tenderness of her abdomen. She undergoes a limited abdominal ultrasound which reveals a 1.4 cm gallbladder polyp. What is the next best step in the management of this patient?

• A. Barium swallow study
• B. Magnetic resonance cholangiopancreatography (MRCP)
• C. Endoscopic retrograde cholangiopancreatography (ERCP)
• D. No further treatment required
• E. Cholecystectomy (Correct Answer)

Minimally Invasive Surgery Explanation: ***Cholecystectomy*** - This patient has a **gallbladder polyp** measuring **1.4 cm**, which is above the threshold for concern (typically >1 cm), indicating a higher risk of **malignancy**. - Given her recurrent **right upper quadrant pain**, even if dull and self-resolving, surgical removal (cholecystectomy) is the recommended management to prevent complications and rule out cancer. *Barium swallow study* - A **barium swallow study** is used to evaluate the **esophagus** and **upper gastrointestinal tract** for conditions like dysphagia, reflux, or strictures. - It is not indicated for the evaluation or management of gallbladder polyps or right upper quadrant pain of biliary origin. *Magnetic resonance cholangiopancreatography (MRCP)* - **MRCP** is a non-invasive imaging technique primarily used to visualize the **biliary and pancreatic ducts** for conditions like gallstones, strictures, or tumors. - While it can provide more detail on biliary anatomy, it is not the primary intervention for a large gallbladder polyp with symptomatic presentation; surgery is more definitive given the size. *Endoscopic retrograde cholangiopancreatography (ERCP)* - **ERCP** is an invasive endoscopic procedure used to diagnose and treat conditions of the **biliary and pancreatic ducts**, often involving stone removal or stent placement. - It carries risks and is typically reserved for therapeutic interventions or when MRCP is inconclusive, and not for the initial management of a symptomatic gallbladder polyp. *No further treatment required* - A **gallbladder polyp over 1 cm** carries a significant risk of **malignant transformation** and requires intervention. - This patient also has recurrent symptoms, which further supports the need for treatment rather than watchful waiting, to alleviate symptoms and address the polyp.

Minimally Invasive Surgery US Medical PG Question 10: A 45-year-old woman comes to the emergency department complaining of abdominal pain for the past day. The pain is situated in the right upper quadrant, colicky, 8/10, and radiates to the tip of the right shoulder with no aggravating or relieving factors. The pain is associated with nausea but no vomiting. She tried to take over-the-counter antacids which relieved her pain to a certain extent, but not entirely. She does not smoke cigarettes or drink alcohol. She has no past medical illness. Her father died of pancreatic cancer at the age of 75, and her mother has diabetes controlled with medications. Temperature is 38°C (100.4°F), blood pressure is 125/89 mm Hg, pulse is 104/min, respiratory rate is 20/min, and BMI is 29 kg/m2. On abdominal examination, her abdomen is tender to shallow and deep palpation of the right upper quadrant. Laboratory test Complete blood count Hemoglobin 13 g/dL WBC 15,500/mm3 Platelets 145,000/mm3 Basic metabolic panel Serum Na+ 137 mEq/L Serum K+ 3.6 mEq/L Serum Cl- 95 mEq/L Serum HCO3- 25 mEq/L BUN 10 mg/dL Serum creatinine 0.8 mg/dL Liver function test Total bilirubin 1.3 mg/dL AST 52 U/L ALT 60 U/L Ultrasonography of the abdomen shows normal findings. What is the best next step in management of this patient?

• A. Emergency cholecystectomy
• B. CT scan
• C. Reassurance and close follow up
• D. Cholescintigraphy (Correct Answer)
• E. Percutaneous cholecystostomy

Minimally Invasive Surgery Explanation: ***Cholescintigraphy*** - The patient presents with **right upper quadrant pain**, fever, **leukocytosis**, and elevated liver enzymes, pointing towards **acute cholecystitis**. Despite a normal ultrasound, cholescintigraphy (HIDA scan) is the gold standard for diagnosing acute cholecystitis when imaging is equivocal. - Cholescintigraphy can assess the **patency of the cystic duct**, which is often obstructed in acute cholecystitis, by observing whether the gallbladder fills with tracer. *Emergency cholecystectomy* - **Acute cholecystitis** usually requires cholecystectomy, but it's typically performed **after confirmation** of the diagnosis, often after a period of stabilization with antibiotics and fluids, not immediately as an emergency for this stable patient. - There is no evidence of severe complications such as **gallbladder perforation** or gangrene that would necessitate immediate emergency surgery without further diagnostic confirmation. *CT scan* - A **CT scan** is not the primary imaging modality for acute cholecystitis as it is **less sensitive** than ultrasound or cholescintigraphy for detecting gallbladder inflammation and cystic duct obstruction. - While CT can identify complications such as abscess formation or perforation, the initial diagnostic work-up should focus on confirming the inflammation of the gallbladder itself. *Reassurance and close follow up* - The patient's symptoms (severe **colicky pain**, fever, **leukocytosis**, elevated liver enzymes) indicate an **acute inflammatory process** requiring active medical management and diagnosis, not mere reassurance. - Delaying appropriate diagnosis and treatment for acute cholecystitis can lead to severe complications like gallbladder perforation, sepsis, or cholangitis. *Percutaneous cholecystostomy* - **Percutaneous cholecystostomy** is generally reserved for patients with acute cholecystitis who are **too unstable for surgery**, or in cases where surgical risk is very high. - The patient is hemodynamically stable and does not have contraindications for surgery, making a definitive surgical approach (after diagnosis) preferable over a temporizing measure.

Minimally Invasive Surgery Flashcard 1 of 8

Question: EF < _____% and MI within _____ months are absolute contraindications to non-cardiac surgery

Answer: 35

Extra Information:  https://onlinemeded.org/spa/surgery?ref=anki 

Minimally Invasive Surgery Flashcard 2 of 8

Question: The iliohypogastric nerve is commonly injured due to post abdominal surgery _____

Answer: sutures

Minimally Invasive Surgery Flashcard 3 of 8

Question: The _____ ligaments are clamped and divided to enter the peritoneum of the broad ligament during a hysterectomy

Answer: round

Minimally Invasive Surgery Flashcard 4 of 8

Question: Cutaneous healing by _____ intention is when the wound edges are brought together (e.g. suturing a surgical incision)

Answer: primary

Minimally Invasive Surgery Flashcard 5 of 8

Question: Echinococcus granulosus cysts are injected with _____ during surgery to kill larvae and prevent spread/anaphylaxis

Answer: ethanol

Minimally Invasive Surgery Flashcard 6 of 8

Question: If a patient has a varicocele, consider surgical ligation or _____ if associated with pain or infertility

Answer: catheter embolization

Minimally Invasive Surgery Flashcard 7 of 8

Question: Umbilical hernias are soft, benign, and _____

Answer: reducible (reducible or non reducible?)

Minimally Invasive Surgery Flashcard 8 of 8

Question: What is the treatment for Stanford type A aortic dissection? _____

Answer: Surgery